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Thread: Pump size question

  1. Back To Top    #1

    Join Date
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    Pump size question

    I have a friend that has a 20x40 irregular shape pool 40,000 gallons approx and their pump is on its way out. They are looking for a new one but currently have a 3/4hp pentair pump should they be looking at the same size or should they look for something a little bigger? What size do you think they should go with?

    Also would they be able to go bigger or is the plumbing restrict them to a certain size pump?
    Inground Grecian 20,000 gallons vinyl liner
    Hayward 250 BTU Propane heater
    Hayward DE Filter
    1 HP Northstar Pump
    Spill Over Spa

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    Mod Squad Bama Rambler's Avatar
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    Re: Pump size question

    Do you know if they have a 2-speed pump?

    If they haven't been having problems I'd go back with what they have. If I were going to do other than that I'd suggest a 1 hp 2-speed.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  3. Back To Top    #3

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    Re: Pump size question

    They have a 1 speed pump and the 3/4 hp has not given any pool condition problems that I know of. I did mention that they may want to get a 2 speed pump. With that do you just run it longer to make of for the fact that the pump is running slower? Does this negate the slower speed on the pump? What would you need the higher speed for?

    Thanks for the help.
    Inground Grecian 20,000 gallons vinyl liner
    Hayward 250 BTU Propane heater
    Hayward DE Filter
    1 HP Northstar Pump
    Spill Over Spa

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    Mod Squad Bama Rambler's Avatar
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    Re: Pump size question

    You need the high speed for running things like cleaners, fountains, or other high flow devices.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    JasonLion's Avatar
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    Re: Pump size question

    The usual way to run a two speed pump is to run it on low speed for twice as long as you were previously running on high speed. That will move the same total amount of water and use noticeably less electricity, despite the longer run time.

    High speed can be handy for several things. You often need to use high speed to prime the pump and to backwash the filter (if your filter needs backwashing). Occasionally, high speed is needed for vacuuming, though some pools can vacuum just fine on low speed.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. Back To Top    #6

    Join Date
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    Re: Pump size question

    Thanks everyone I will pass the information along.
    Inground Grecian 20,000 gallons vinyl liner
    Hayward 250 BTU Propane heater
    Hayward DE Filter
    1 HP Northstar Pump
    Spill Over Spa

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